2-nitro-1, 1-bis (p-chlorophenyl) alkanes, and insecticidal compositions containing same



Patented July 25, 1950 UNITED STATES PATENT OFFICE Z-NITRO-Ll-BIS KANES,

(P-CHLOROPHENYL) AND INSECTICIDAL COMPOSI- TIONS CONTAINING SAME Henry B. Hass, West Lafayette, Ind., and Robert T. Blickenstail, Wyoming, Ohio, assignors to Purdue Research Foundation, La Fayette, Ind,

a corporation of Indiana No Drawing. Application November is, 1948, Serial No. 60,834

6 Claims.

tages, among the most serious of which is the fact that they are highly selective in their action. This means that the choice of an insecticide must be governed by theparticular insect pest against which it is to b used. Even closely related insecticides have selective insecticidal properties which difier unpredictably, or are even totally dissimilar. Moreover, certain insects are virtually immune to all known insecticides, when i applied in economically feasible quantities.

Further disadvantages frequently prevent an insecticidal agent with adequate killing properties from being used commercially. The agent may, for example, produce a discoloration of, or

impart a taste to the infested vegetable or ani mal, rendering them unsuitable for marketing. Also, the agent may be difiicult to apply or dangerous both during and after application. Then, there is the factor of cost, which is a prohibitive disadvantage for many insecticidal agents. Another disadvantage directly related to that of high cost is that many agents must be applied in relatively strong concentrations. As a general rule, it may be stated that the lower the required toxic concentration, the lower the cost of using an insecticidal agent.

The efiicacy of an insecticidal composition is most generally and universally measured in terms of per cent kill. It goes without saying that such measurements must be for a definite period of time, and that other conditions must be carefully controlled and standardized to permit comparisons of results. For flying insects, the efiicacy may also be measured in terms of per cent "knock-down." Many prior art insecti-- sides possess kill and knock-down properties in dil fering degrees. For this reason, it may be necessary to combine two or more compounds in and kill. In general, an insecticide possessing bot-h properties in a high degree would have greater utility, than another insecticide which was comparable in only one property.

We have now discovered that compounds having the general formula:

wherein R is an alkyl chain selected from the group CH3 and C2H5 possess strong insecticidal properties; and, in particular, that these compounds are especially eiiective killing agents for the milkweed bug, which could not be killed by practical quantities of previously knowninsecticides. Also, we have discovered that our new compounds are unusually effective against flies. the Mexican bean beetle, the pea aphid, and the southern army worm. We have also discovered that not only do our compounds produce a high per cent kill, when used in low concentrations against flies; but also that they possess excellent "knock-down properties.

Our invention comprises two compounds; namely, 2-nitro-1,l-bis(p-chlorophenyl)propane and 2-,nitro-1,1-bis(p-chlorophenyl) butane. The 2-nitro-l,l-bis(p-chlorophenyl)propane of our invention may be prepared as follows:

One thousand four hundred twenty ml. of sulfuric acid (2-3 per cent S03) was mixed with 9.35 moles (1050 g.) of chlorobenzene and cooled to 10 C. in an ice-salt bath; Three and eighttenths moles (820 g.) of 1-p-chlorophenyl-2- nitro-l-propanol was then added dropwise to the thoroughly stirred mixture at such a rate that the temperature remained between 10 and 15" C. After the addition of the nitro'alcohol, the mixture was stirred at room temperature for 10 hours. then poured over cracked ice and allowed to stand several hours.

The mixture was extracted with ether and the ether solution washed with sodium bicarbonate solution, saturated sodium bisulfite solution, and water, The ether was then evaporated and the residue steam distilled. The residue from the steam distillation was dissolved in ether, the ether solution dried with anhydrous sodium sulfate, and the ether evaporated. 'I he residue was a viscous oil which gradually crystallized. After several recrystallizations from absolute ethanol, 3. white solid remained which melted at 80.5-1.5 C. The yield of 1,1-bis-p-chloropheny1-2-nitroorderto achieve effectively both knock-down 55 propane was 437 g., 37 per cent.

hydroxide in 800 ml. of water, which was cooled in an ice-salt bath.

These solutions were mixed and stirred at room temperature for 12 hours, then poured into a separatory funnel. The two layers were separated, the aqueous layer was extracted with ether,

and the ether portion was added to the organic layer. The ether solution was extracted with saturated sodium bisulflte solution until the unreacted aldehyde was removed. The ether solution was then dried with anhydrous sodium sulfate and the ether evaporated, The conversion to 1-p-chlorophenyl-2-nitro-l-propanol was 820 g., 95 per cent.

The 2-nitro 1,1 bis(p-ch1orophenyl) butane may be prepared by condensing l-p-chlorophenyl- 2-nitro-l-butanol with chlorobenzene, following the same procedure as that given above for condensing l-p-chlorophenyl 2 nitro-l-propanol with chlorobenzene. Also, the l-p-chlorophenyl- 2-nitro-1-butanoi may be prepared by a condensation of p-chlorobenzaldehyde with l-nltropropane, substantially as described above for the preparation of l-p-chlorophenyl-2-nltro-l-propanol.

The compounds of our invention are not uniformly toxic to different insects, although they both have approximately equal toxicity for the same kind of insects. Thus, the lowest quantity of our compounds which can be used effectively in insecticidal compositions depends primarily on the particular insect to be combated. The required concentration also depends to some extent on such factors as the carrier used, method of application, and location of insects, In general, however, compositions containing about 2.

down agent in insecticides. Also, five per cent concentrations in a dust have been found particularly effective in killing the milkweed bug,

' an insect which is particularly diflicult to kill,

and has a virtually complete immunity to many other insecticides. For many common insect pests, concentrations much lower than 2 per cent can be used, Tables I and 11 show that quite low concentrations of 2 nitro- 1,1 bis (p-chlorophenyl) propane and 2-nitro-l,1-bis(p-chlorophenyl) butane continued to give a high per cent Each entry in Tables I and 11 below is an average of several replications. The testing procedure used for female houseflies was substantially as follows:

Solutions of various concentrations were pre- A 1.0 per pared by dissolving the active agents in a solvent as a carrier. Adult flies reared in the laboratory under constant conditions were introduced into replicated spherical cages, Each cage was then placed on a revolving turntable,- and the flies subjected to an atomized spray under constant pressure until 1.0 ml. was delivered per cage. Immediately after the flies in a cage were sprayed. they were transferred to an observation cage, in which they were maintained under constant conditions for twenty-four hours, At the end of that time the number of dead flies was counted.

For the Mexican bean beetle, the pea aphid, and the southern army worm the following procedure was used: Different quantities of the active insecticidal agent were uniformly mixed with a solid inert carrier in the form of a finely ground powder. The dust thus obtained was applied in 0.2 gram amounts to host plants to which the insects were then transferred. The host plants utilized for the Mexican bean beetle and the southern army worm were cranberry beans, while broad Windsor beans were used for th pea aphid. At the end of forty-eight hours for the southern army worm, and seventy-two hours for the Mexican bean beetle and the pea aphid, the percentage of dead insects was determined.

In the case of the milkweed bug, 0.4 gram of the dust carrying the insecticidal agent was blown directly onto the insects and the latter then transferred to clean cages into which milkweed seeds had been introduced as food. After seventy-two hours, the percentage of dead insects was determined.

TABLE I 2-mtro-1,1 -bis(p-chlorophen1ll) propane Per Cent Average Insect Concenm' Per Cent tion of Km Toxlcant TABLE II Z-mtro-I ,1 -bis (p-chlorophenyl) butane Per Cent Concentration of Toxicant Film Mexican Bean Beetle sssaeses Q3 Do Pea Aphid Army wm'm Milkweed Bug cause our compounds are relatively insoluble.

Household spray kerwene (ultrasene) was used as the carrier in the fly tests reported above. Effective concentrations can be produced in other liquid carriers such as the lower aliphatic alcohols (methyl, ethyl, propyl, butyl), chlorinated hydrocarbon solvents (carbon tetrachloride, dichloromethane, trichloroethane) and aromatic hydrocarbons (benzene, xylene, toluene). Aqueus suspensions of about one per cent can be made and are unusually'eflective in some cases. For example, a 0.5% aqueous suspension of 2-nitro- 1,1 bis(p-chlorophenyl) propane gave a 97% "kill" of the pea aphid in 72 hours. Also, aqueous emulsions may be advantageously used.

As a solid vehicle we may employ any of the forms of powdered aluminum silicate which are commonly employed in insecticidal compositions, such as pyrophyllite, bentonite, fullers earth, kie'seiguhr, kaolin, and talc. In the tests reported above, except for flies, prophyllite was employed asthe carrier. When solid carriers are used, there is, of course, no limit to the obtainable concentrations.

In addition toeither a liquid or solid carrier, other killing agents may be combined with our compounds; Low solubilities might limit the use of certain additional agents in a liquid carrier; but, in general, our compounds may be used in conjunction with killing agents such as pyrethnun, rotenone, derris extract, nicotine, and organic thiocyanates.

' Economically, our compounds possess the great advantage of remaining highly toxic in very low concentrations. Another advantage of our compounds, not mentioned elsewhere is that they do not produce a discoloration of vegetables such as squash and member. Furthermore, our compounds are especially safe; and, when it comes to performance combined with safety, our com- 6 pounds are a great improvement over similar prior art insecticides.

Now having described claim is:

1. The compounds of the general formula:

about .062 to about 5.0% of a compound of the eneral formula:

WOQFE'R Cy H wherein R is an alkyl chain selected from the group CH3 and Celia, and a carrier therefor.

5. The composition of claim 4 where the carrier is a petroleum distillate.

6. The composition of claim 4 where the carrier is a powdered aluminum silicate.

HENRY B. HASS. ROBERT T. BLICKENSTAFF.

REFERENCES CITED The following references are of record in the our invention, what we Certificate of Correction Patent No. 2,516,186

It is hereby HENRY-B. HASS ET AL. certified that error appears in the printed specification of the above file of this patent:

UNITED STATES PATENTS Number Name Date 2,397,802 Muller Apr. 2, 1948 July 25, 1950 numbered patentrequirmg correction as follows:

Column 5, line 20, for prophyllite read pyrophyllite;

and that the said Letters Patent should be r may conform to the record of the case in th Signed and sealed sad as corrected above, so that the same e Patent Oflioe. this 31st day of October, A. D. 1950.

THOMAS F. MURPHY, 

1. THE COMPOUNDS OF THE GENERAL FORMULA:
 4. AN INSECTICIDAL COMPOSITION COMPRISING FROM ABOUT .062 TO ABOUT 5.0% OF A COMPOUND OF THE GENERAL FORMULA: 